How much electricity do eco ventilators save in an Alwar oil mill compared with exhaust fans?

The Bureau of Energy Efficiency (BEE) Alwar manual books 0.75 kilowatts (kW) for each exhaust fan running 7,000 hours: 5,250 kilowatt hours (kWh) and rupees (Rs) 25,200 a year at Rs 4.8 a kWh. A wind driven eco ventilator draws nothing and costs Rs 3,500 to 4,000, so the manual prints a three month payback.

The fan sum in the manual

• The manual describes oil fumes that make workers sweat and their eyes itch at a plant temperature of 30 degrees Celsius, so exhaust fans run all shift. Its sum puts one fan at 0.75 kW, though its own text says these fans are in the range of 1 to 1.5 kW.
• Running hours 7,000 a year, tariff Rs 4.8 a kWh. 0.75 kW x 7,000 hours = 5,250 kWh, which at Rs 4.8 is Rs 25,200, printed as Rs 0.25 lakh a fan.
• An eco ventilator has no powered part, so its electricity is nil, and the manual says it lasts a very long time. Price Rs 3,500 to 4,000 each.

What the cluster totals say

For all units in Alwar and Sawai Madhopur the manual prints a saving of about 2.2 lakh kWh and Rs 10.91 lakh, for Rs 2.34 lakh spent, and a payback of three months. 2.2 lakh kWh is 220,000 kWh, which is about 42 fans of 5,250 kWh each. That count is our arithmetic, not the manual's.

• Rs 10.91 lakh over 2.2 lakh kWh is Rs 4.96 a kWh, not the Rs 4.8 used in the single fan sum. At Rs 4.8 the saving would be Rs 10.56 lakh.
• Rs 2.34 lakh over 42 fans is about Rs 5,570 a fan, which is 1.4 to 1.6 ventilators at the printed Rs 3,500 to 4,000 each. The manual does not say how many ventilators replace one fan. A foundry report on this site uses six for each fan, so count the ventilators your shed needs before you rely on the three months.
• Payback: 2.34 x 12 / 10.91 = 2.6 months, which the manual rounds to three.

What the manual says to watch

• Use the ventilators and switch the exhaust fans off. The manual says a running fan cancels the pressure difference the ventilator works on.
• Some units cannot fit them because of a reinforced concrete roof.
• The kolhu section needs more ventilators than the expeller section, since the kolhu gives more oil fumes.
• Few suppliers serve the area because of its remote location, and the manual says small issues may come from workers, because of the psychological effects of not using exhaust fans.

One fan and the cluster total, with carbon dioxide (CO2)

• One fan: 0.75 kW x 7,000 hours = 5,250 kWh a year
• Money: 5,250 x Rs 4.8 = Rs 25,200
• CO2 at the financial year (FY) 2025-26 grid factor of 0.675 kg a kWh: 5,250 x 0.675 = 3,544 kg, about 3.5 tonnes
• At the manual's own factor of 0.86 tonnes for every 1,000 units: 5,250 x 0.86 = 4,515 kg
• Cluster total: 220,000 kWh x 0.675 = 148,500 kg, about 149 tonnes

Fan power, hours and tariff are the manual's, at its date. Your own fan's rating plate and run hours replace them.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so your bills before and after the change are on file to compare. It does not measure fans or count ventilators.

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• Do the Alwar manual totals add up
• Carbon calculators

Sources: Bureau of Energy Efficiency and Confederation of Indian Industry, Manual on energy conservation measures in the Alwar oil mill cluster (SAMEEEKSHA), Central Electricity Authority, CO2 Baseline Database for the Indian Power Sector (grid factor 0.675 kg CO2 per kWh, financial year 2025-26)

Last reviewed 2026-11-06. Figures are the manual's, from the Bureau of Energy Efficiency Small and Medium Enterprises (SME) programme, at its tariff of Rs 4.8 a kWh. Check your tariff and a ventilator quote before you rely on the payback.